This invention relates to an articulated and balanced manipulator.
Systems for remote handling operations include the so-called master-slave manipulators which are already well-known and in wide use. A manipulator of this type comprises a master portion controlled by the operator and a slave portion which reproduces the movements of the master portion, a gripping device or tool being carried by the manipulator at the slave end. Master-slave manipulators are often designed for work conducted within enclosures or caves which are usually shielded. The thickness of the shielding wall is variable but always ranges from a minimum thickness of 5 centimeters to a thickness of 1 meter. The master arm remains outside the enclosure and the manipulator extends through the wall.
When the operator of a master-slave manipulator actuates the control handle by hand, the same movements are reproduced by the tong unit or gripping device. Conversely, the reversibility of the transmission between the master portion and the slave portion produces a feedback force. The manipulator consequently enables the operator to sense the efforts exerted or encountered by the tool or gripping device at the slave end and in particular to feel the mass or weight of objects being handled. Furthermore, a manipulator of this type is balanced with respect to gravity and is consequently indifferent in the case of all his movements when operating on no load.
In another known category are the so-called power manipulators which are usually driven by an electric motor and penetrate completely within the installations instead of passing through the shielding wall as in the case of manipulators of the previous type.
Finally, there is another known type of power manipulator having bilateral control which produces the same feedback forces and the same integrated direct control from a single operating handle as the manipulators of the first type referred-to in the foregoing.
The above-mentioned first type does not permit the handling of large masses; this is the case in particular if the object to be handled is not a variable object contained within the work enclosure but becomes an object of constant and substantial weight such as a television camera designed for surface inspection or a system for spraying with water at high pressure for decontamination purposes.
In the first and third cases mentioned above, the object or tool employed has to be carried continuously by the operator who is thus subjected to considerable fatigue. Power manipulators cannot readily operate within enclosures of very small size as is the case in particular when it is desired, for example, to decontaminate portions of primary circuits of nuclear reactors by means of water under pressure or to carry out inspections in such circuits.
To this end, the manipulator in accordance with the invention is intended to carry out balancing of a tool other than a tong unit while ensuring that mobility of the tool within a sealed enclosure is achieved. The manipulator in accordance with the invention further permits of penetration into the interior of the enclosure in any desired direction through an orifice having small dimensions. Furthermore, balancing of the manipulator is ensured not only with respect to control of the load being handled but also with respect to its handling point for introduction of said manipulator into the enclosure or more precisely the introduction of its slave end.
To this end, the manipulator in accordance with the invention is continuously balanced irrespective of the deformations of said manipulator when this latter is attached to the wall of the enclosure in which it is desired to operate. The manipulator as a whole is also balanced at the time of initial installation and of transportation outside the enclosure with respect to a supporting shaft. In simplified terms, this result is obtained by giving homothetic shapes to the different elements of the slave arm and to the different elements of the master arm, said master arm being adapted to carry at least one balance weight.